Activism is a specific type of political participation that is typically associated with collective efforts to promote, hinder, or intervene in social or environmental change to create a better society. In LAM research and practice, activism is on the agenda all over the Western world, both as a criticism of neutral LAM work and as a new way of working with underrepresented groups and causes in LAMs. In this chapter, we discuss the notion of neutrality and argue that there is a close connection between “the myth of neutrality” and LAM activism. After this, we argue how activism differs from cultural policy and the concept of cultural democracy. The chapter offers a definition of LAM activism and discusses examples of how, and to what extent, LAMs act as activists. Finally, the chapter discusses activism’s implications for the legitimacy of libraries, archives, and museums.